Predistortion is a technique used in communications systems to improve the linearity of power amplifiers. Because power amplifiers can have nonlinear input/output characteristics, predistortion is used to linearize the input/output characteristics of the power amplifier. In essence, “inverse distortion” is introduced into the input fed to the power amplifier, thereby cancelling the non-linear characteristics of the power amplifier.
Current predistortion technologies used to linearize power amplifiers in mobile communication systems are mainly analog predistorters implemented at IF/RF by means of analog circuitry and a digital predistorter at baseband with digital signal processing (DSP) techniques.
The analog predistorter is based on the principle of error subtraction and power matching to produce linearization of the power amplifier. Because nonlinear characteristics of power amplifiers can be complicated and involve many variables, analog predistortion results in less than optimal predistortion accuracy and consumes significant power.
Despite the progress made in predistortion technologies, there is a need in the art for improved methods and systems for digital predistortion systems.